This invention relates to microcircuit packages, and more particularly relates to a metal assembly for packaging hybrid microcircuits having only the grounding and insulated leads gold plated, and also relates to a method for producing such an assembly.
Packaging for hybrid microcircuits often includes a metal header for supporting the circuit, and a plurality of leads for external connection to the circuit. The leads typically are arranged in rows along opposite sides of the header to flank the circuit and have heads positioned at a height to be coplanar with the circuit substrate for easy access. The leads extend through the bottom wall of the header and are normally insulated from the metal header by a metal sealing glass such as a borosilicate. The leads and header typically have electroplated layers of nickel, and the leads have a further electroplated gold layer.
In some cases, it is preferable to also have gold plated grounding leads which may be electrically connected to the metal header. In mass production, however, it has been found difficult to gold plate these leads without also unnecessarily gold plating the metal header to which they are connected.
Plating the leads prior to their assembly in the header is not a practical alternative, due to the necessity for a preoxidized, plating-free metal surface to achieve an effective glass-to-metal seal.
Accordingly, it is an object of the invention to provide an assembly for packaging microcircuits comprising a metal header and metal leads extending from the header, at least some of the leads forming a glass-to-metal seal with the header, and all of the leads being gold plated.
It is a further object of the invention to provide a method suitable for mass producing such an assembly without gold plating the header and without interfering with the integrity of the glass-to-metal seals.